Automatic fire-alarm system.



A. H. MoNEIL.

AUTOMATIC FIRE ALARM SYSTEM.

APPLIGATION FILED DEC. 1, 1911.

1 ,O47,264, Patented De'c. 17, 1912.

I n ju- H UNITED STATES PATENT OFFICE.

ALFRED HENRY MONEIL, OF CHINGFORD, ENGLAND, ASSIGNOR TO THE ASSOCIATED FIRE ALARMS LIMITED, OF LONDON, ENGLAND.

-AUTOMATIC FIRE-ALARM SYSTEM.

Application filed December 1, 1911.

Specification of Letters Patent.

Patented Dec. 1'7, 1912. Serial No. 663,328.

To all whom it may concern:

Be it known that I, ALFRED HENRY Mo- NEIL, a subject of the King of Great Britain and Ireland, residing at- 43 Beech Hall road, Chingford, Essex, England, have invented certain new and useful Improveor normal Variations in temperature has been effected by' means of a small leak into the open or into a closed reservior.

Now according to my invention I connect the tube containing an expansible fluid, to two boxes, each having a flexible diaphragm and the connection to one diaphragm ismade very small, and two spring contacts are arranged above the diaphragms and the differential movement of the two contacts is used to operate the alarm circuit.

In one way of carrying out this invention, the small tube containing the volatile liquid is connected at its end to two boxes closed by flexible diaphragms, one of the said connections being through a restricted orifice or other device that allows only of leakage past it. Above each diaphragm a movable contact is supported, that over the reservoir having the restricted passage be-. mg at any desired distance in front of the other. When one contact overtakes the other, afire signal is given. A bridge piece passes over both contacts and carries a screw eitheras a mechanical stop or as a contact so that an alarm may also be actuated at any desired degree of temperature;

In the accompanying sheet of illustrative drawings, Figure 1 is a sectional elevation of the differential contact apparatus constructed according to this invention, and Fig. 2 is a diagram of the connection of the fire alarm circuit.

The apparatus consists of a metal base a with one free passage 5 and one restricted passage 0 leading to two hollow reservoirs d and e which are provided with thin flexible metal diaphragms d and e. Above the diaphragms d and 0 two spring contact strips 1 and g are mounted on supports f and g. The contact strips are insulated from the supports by ebonite washers and from the diaphragms by ebonite points on the adjusting screws h and a, and their ends which overlap are provided with platinum contact points 7', la. Situated above the contact points 74 and is a bridge carrying an adjustable stop screw and contact Z intended to limit the motion of the contact strips 1 and g. To the passage 7) a small cylinder m is connected, which with its plunger n is intended to apply an increased pressure I when desired for the purpose of testing the apparatus. The ends of the passages 79 and c are connected tothe extremities of the metal tube 0 which passes throughout the I area to be p otected.

The action of the apparatus is as follows: In the event of a fire, the rapid increase of temperature produces a corresponding increase in pressure in the tube 0 which" causes the liquid contained therein to flow to the reservoirs d and 0. Now owing to the restriction in the passage 0 leading to the reservoir c, the effect produced on the diaphragm will be greater in the case of diaphragm d and so the spring f will overtake spring 9 and eifect a contact between the two. With ordinary rises in temperature the increase in pressure will be so gradual that the liquid will, flow equally into both reservoirs and the contact points will both move, but not approach one another. Thus noalarm is given for ordinary temperature rises until a certain limit is reached, this point being determined by the posit-ion of the stop Z.

The method of connecting the apparatus with the battery and bell is diagrammati cally shown in Fig; 2. The two cont-act strips f g are connected in series with the battery and bell and the limiting stop point Z-is also connected to the. strip 1. By this arrangement'it will be seen that an alarm is given if the contact strips touch one another, or if the upper contact strip touches the limit stop Z.

What I claim and desire to secure by Letters Patent is 1. .A temperature alarm apparatus comprising pressure responsive devices, one of said devices having a restricted passage leading thereto, and the other an unrestricted or free passage, a detector piping communicating with the free and the restricted passages, a circuit including an alarm device, a source of current, and a contact for actuation by each of said responsive devices for closing circuit by differential movement of said cont-acts, substantially as described.

2. A temperature alarm apparatus comprising pressure responsive devices, one of said devices having a restricted passage leading thereto and the other an unrestricted or free passage, detector piping communicating with the free and the restricted passages, a circuit including an alarm device, a source of current and a contact for actuation by each of said devices for closing 15 circuit by differential movement of said contacts, and an auxiliary contact in said circuit arranged in the path of one of the first named contacts, substantially as described.

In testimony whereof I have affixed my 20 signature, in presence of two witnesses.

ALFRED HENRY MGNEIL.

Witnesses:

NED Z. CURzoN, HUBERT D. J AMESON. 

